The present invention relates to reclosable bags manufactured on form, fill and seal machines and, more particularly, to a reclosable bag manufactured on a form, fill and seal machine which includes a strip of material having a front surface thereof releasably adhered to the interior of the bag and a rear surface thereof permanently adhered to the interior of the bag.
It is well-known to manufacture conventional flexible bags on a vertical form, fill and seal (VFF) machine, as well as on a horizontal form, fill and seal (HFF) machine. Thus, for example, in a VFF machine the bag is manufactured by shaping a web of bag material such as a plastic film into a tube, making a parallel side seal in the tube and then a transverse bottom end seal in the tube, filling the open-ended tube with product, and then making a transverse top end seal to enclose the product. A cut is then made at or above the top end seal to render the packaged product.
An opening location is typically provided parallel to the top and bottom transverse end seals in the bag material for opening of the bag. The opening location often comprises a line of perforations or a weakened line formed in the bag material where, by tearing or severing along the opening location, access to the product is gained. The opening location also can comprise a panel formed in the bag material removable by grasping a pull tab and tearing along a perforated outline of the panel.
It is often desirable to use only a portion of the packaged product and retain the rest of the product within the bag. To this end, Yeager U.S. Pat. No. 5,461,845 discloses a bag that is intended to be formed on a VFF machine which includes a fastener assembly having two interlocking profile strips each of which is independently attached to the inside surface of the bag material on opposite sides of an opening location. Yeager U.S. Pat. No. 5,806,984 discloses a similar reclosable bag having the same two interlocking profile strips forming the reclosable assembly; however, the ""984 Patent further discloses that the two strips are peelably sealed together to form an airtight seal until such time as the bag is first opened. Thereafter, the interlocking profile strips are solely utilized to reclose the bag.
An actual method for making a reclosable bag on a VFF machine utilizing interlocking profile strips is disclosed in McMahon et al. U.S. Pat. No. 4,909,017, wherein the pair of interlocking profile strips are mated and then attached to the web of bag material. Specifically, one of the interlocking profile strips is permanently sealed to the web of bag material to extend transversely between the longitudinal side edges thereof with the other interlocking profile strip simply remaining interlocked with the first strip. The web is then filled and formed into bags on a VFF machine as shown in FIG. 1 of McMahon et al. Furthermore, when making the top end seal, the interlocking profile strip which is not yet sealed to the bag material is then permanently sealed to the bag material at a location on the back panel of the bag as shown in FIG. 5. A similar method for making a reclosable bag on a VFF machine utilizing interlocking profile strips is disclosed in Christoff et al. U.S. Pat. No. 4,655,862.
Another type of reclosable bag intended to be formed on a VFF machine is disclosed in FIGS. 18 and 19 of Sanders U.S. Pat. No. 4,709,399, wherein a single surface of a strip of material is adhered only to a single bag wall in covering relation to an opening formed in a panel of the bag wall. Furthermore, only a portion of the strip is releasably sealed to the single bag wall, with the remaining portion of the strip being permanently sealed to the single bag wall. A similar bag is disclosed in Sanders U.S. Pat. No. 4,913,293. Unlike the aforesaid reclosable bags, the bags of Sanders do not utilize interlocking profile strips but, instead, utilize only a single strip of material.
The present invention provides yet two additional, unique methods for making reclosable bags specifically on form, fill and seal machines including both VFF machines and HFF machines.
Briefly described, the present invention includes the method of making a reclosable bag on a form, fill and seal machine including the steps of: applying a strip of material to a web of bag material to extend transversely relative to longitudinal edges of the web, the strip including a front surface releasably applied to the web via a pressure-sensitive adhesive and an exposed rear surface; folding the web about an axis extending parallel to the longitudinal edges thereof; and then, sealing the web to form the bag, including permanently sealing a portion of the web to the exposed rear surface of the strip to form a reclosable transverse end seal of the bag. The strip of material extends less than the width of the web and, preferably, either is slightly less than, equal to, or slightly more than one-half of the width of the web.
Features of this method include: sealing together overlapping portions of the web in a direction parallel to the longitudinal edges of the web to form a side seal of the bag, and sealing together overlapping portions of the web in a direction transverse to the longitudinal edges of the web to define a non-reclosable transverse end seal; filling the bag with product during the step of forming the bag; and folding the web about an axis collinear with a cylindrical feed tube of a VFF machine.
The present invention also includes the additional method of making a reclosable bag on a form, fill and seal machine including the steps of: forming an opening location in a web of bag material having a length extending generally transversely between longitudinal edges of the web; applying a strip of material to the web in covering relation to the opening location, the strip including a front surface releasably applied to the web via a pressure-sensitive adhesive and an exposed rear surface, the front surface extending to opposite lateral sides of the transversely extending opening location; folding the web about an axis extending parallel to the longitudinal edges; and sealing the web to form the reclosable bag, including permanently sealing a portion of the web to the exposed rear surface of the strip. The strip of material extends preferably slightly beyond opposed ends of the transversely extending opening location.
Features of this additional method include: permanently sealing a portion of the web to the front surface of the strip, but only to one side of the opening location; sealing together overlapping portions of the web in a direction parallel to the longitudinal edges and in a direction transverse to the longitudinal edges to respectively form a longitudinal side seal and two non-reclosable transverse end seals; forming a non-reclosable transverse end seal of the bag by permanently sealing the bag material to the rear surface of the strip of material, and to the front surface of the strip of material but only on one side of the opening location; and defining the opening location by a line of weakness formed in the web of bag material extending generally linearly between the longitudinal edges of the web, the line of weakness preferably comprising perforations.
Commensurate with the aforesaid methods of the present invention, the present invention also includes reclosable bags formed on a form, fill and seal machine. Thus, one bag of the present invention includes a sheet of bag material folded and sealed together at a side seal and two end seals to define the bag; and a strip of material disposed parallel and adjacent to an end seal and having a front surface releasably attached to the bag material via a pressure-sensitive adhesive and a rear surface permanently sealed to the bag material.
The other bag of the present invention includes a sheet of bag material folded and sealed together at a longitudinal side seal and two transverse end seals to define the bag; and a strip of material having a rear surface to which said bag material is sealed and a front surface disposed in covering relation to and on opposite sides of an opening location formed in the bag material, the front surface of the strip of material being releasably attached to the bag material at least on one side of the opening location only by way of a pressure-sensitive adhesive. In a feature of this bag, the front surface of the strip is also permanently sealed to the bag material on one side of said opening location.
In a feature of these two bags of the present invention, a transverse end seal and the seal between the bag material and the rear surface of the strip of material are continuous with each other.